1. Field
The present disclosure relates to a method of intercepting voice over internet protocol (VOIP) communications.
2. Introduction
As is known, many companies have deployed Fiber Optic network to its end customers. It uses VOIP means of VOICE communication via Optical Network terminals (ONT's) and Optical Line terminals (OLT's). Session Initiation Protocol (SIP) is used for signaling between the ONT's. RTP/RTCP is used for exchanging voice data packets over IP.
In Gigabit Passive Optical Networks (GPONs) and Broadand Passive Optical Network (BPONs), the voice traffic is transmitted as Real Time Protocol (RTP) payload. Communications Assistance for Law Enforcement Act (CALEA) is a U.S. wire tapping law. The CALEA concerning Voice over IP packets was issued in the U.S. on or about 2006. The inventor is not aware of a standard or specification for the Lawful Interception of Voice over IP (VOIP) packets. Generally, each operator implements its own proprietary lawful intercept procedures.
The problem with proprietary lawful intercept procedures is that there appears to be an absence of proper or standard procedures defined for doing this. Lawful taps are created on Network Routers, switches or in a Session Border Controller which makes the network providers dependant on these network devices for any wire tapping procedures.
This makes it a less scalable solution and the worse part is setting up the lawful intercepting tap for a particular subscriber. This is not an easy and configurable procedure in VOIP networks. This involves a series of steps in identifying the subscriber's contact information details, such as IP address, and then trying to multicast or clone the RTP packet on a switch side and setting up an RTP relay on the network switch to snoop the RTP packet sent and received from that particular IP address, and intercepting these RTP packets and transmit and store all the VOIP packets for future analysis.
In order to set up a lawful interception of voice packets on a Network Switch, there are several factors that have to be favorable for the Network operator to accomplish this task. VOIP packets need to be relayed, for example, each Switch needs to act as a Back-to-Back User Agent, which is a tedious and labor intensive process and can cause end-to-end delay and packet loss. The additional over head of network processing time also needs to be accounted for.
There is a need to provide a standard procedure for lawful interception of VOIP packets in PONs.
There is also a need to provide a simple and robust wire tapping procedure that can be implemented on the Optical Network Devices, instead of doing it in the network, which can allow a lawful intercept procedure on an interceptor-agent premises via the use of Optical Network Terminals (ONTs), for example.
It would be considered an improvement in the art, if there were a relatively simple, repeatable and scalable method for lawful interception of VOIP communications.
Thus, a method that addresses these issues and problems would be considered an improvement in the art.
To help the reader, a table of commonly used acronyms is provided below.
Table of Acronyms:
    BPON Broadband Passive Optical Network    Codec Program that is capable of encoding/decoding a digital media stream    FTTP Fiber To The Premises    GPON Gigabit Passive Optical Network    ITU-T International Telecommunication Union    Jitter A measure of Average variation from the Network Mean Latency    Latency It is a measure of time delay experienced in a System    OLT Optical Line Terminal    ONT Optical Network Terminal    PON Passive Optical Network    POTS Plain Old Telephony Service    RTP Real Time Protocol    RTTP Real-time Transport Protocol    RTCP Real-time Transport Control Protocol    RTCP SR RTCP Sender Reports    RTCP RR RTCP Receiver Reports    SBC Session Border Controller    SDP Session Description Protocol is a format for describing multimedia streams    SID Silence Insertion Descriptor    SIP Session Initiation Protocol    SIP UA SIP User Agent    Voice Switch Switch that controls VOIP call routing and management, such as a CS2K or Broadsoft Switch